The aim of this study was to investigate the effects of joint mobility on healthrelated physical fitness in healthy young adults. One-hundred and forty-six undergraduate physiotherapy students, aged 17 and 26 years participated in this study. Fifty two percentage of the sample was female. Joint mobility was assessed by using Beighton and Horan Joint Mobility Index (BHJMI). All subjects were divided into three groups according to the their BHJMI scores; hypomobil (0 to 2 score), normal (3 to 4 score) and hypermobil (5 to 9 score). Health-related physical fitness parameters of the sample, including body composition, flexibility, cardiorespiratory endurance, muscular strength and endurance were also assessed. The physical fitness parameters were measured by using BMI, skinfold measurements, sit and reach test, trunk lateral flexion test, Queen’s Colloge Step Test, hand grip strength test, and sit up test. One-way ANOVA, t-test and Kruskal-Wallis tests were used for statical analysis when appropriate. Female students (42%) were much more hypermobile compared with male students (18%). Both female and male hypermobile students’ flexibility test scores including sit and reach and trunk lateral flexion were higher compared with other groups (p ≤ 0.05). On the other hand, group differences were not found in terms of the results of sit up test, dominant side grip strength, non-dominant side grip strength, predicted vO2maks, BMI, and skinfold measures in both female and male students (p ≥ 0.05). Consequently, joint hypermobility leads to increase young adults’ flexibility. On the other hand, the results show that joint hypermobility is not an effective factor on other health-related physical fitness parameters including body composition, cardiorespiratory endurance, muscle strength and endurance.